Luminescence characteristics of Eu²⁺ activated Ca₂SiO₄ Sr₂SiO₄ and Ba₂SiO₄ phosphorsfor white LEDs

This paper investigates the luminescence characteristics of Eu²⁺ activated Ca₂SiO₄, Sr₂SiO₄ and Ba₂SiO₄ phosphors. Two emission bands are assigned to the f--d transitions of Eu²⁺ ions doped into two different cation sites in host lattices, and show different emission colour variation caused by substituting M²⁺ cations for smaller cations. This behaviour is discussed in terms of two competing factors of the crystal field strength and covalence. These phosphors with maximum excitation of around 370nm can be applied as a colour-tunable phosphor for light-emitting diodes (LEDs) based on ultraviolet chip/phosphor technology.